Method for activating a communication mode of a peer communication unit

ABSTRACT

When activating a desired communication mode of an ID communication partner device ( 2 ) from a group of possible communication modes, which group comprises at least a TTF mode and an RTF mode, the ID communication partner device ( 2 ) and at least one other ID communication partner device ( 4 ) are brought into a communication connection, wherein a carrier signal (CS) is output by the at least one other ID communication partner device ( 4 ), which carrier signal (CS) is received by the ID communication partner device ( 2 ), and wherein the carrier signal (CS) is repeatedly designated by at least one mode activation signal (AS) by means of the at least one other ID communication partner device ( 4 ), and wherein the presence of the mode activation signal (AS) is recognized by the ID communication partner device ( 2 ), giving a recognition result signal (RRS), and wherein, as a function of the recognition result signal (RRS), the desired communication mode of the ID communication partner device ( 2 ) is activated.

The invention relates to a method for activating a desired communicationmode of an ID communication partner device from a group of possiblecommunication modes.

The invention furthermore relates to an integrated circuit for an IDcommunication partner device, which integrated circuit comprisesactivation means for activating a desired communication mode of the IDcommunication partner device from a group of possible communicationmodes.

In a sufficiently known communication system, having ID communicationpartner devices, that is used publicly in a number of variantembodiments and is designed as a Reader Talks First (RTF) system, someof the ID communication partner devices are each formed by a transponderor ID tag and other ID communication partner devices are each formed bya communication station. The abbreviation ID in this case stands for theword “identification”. The transponders can be brought intocommunication connection with a communication station. When setting upsuch a communication connection, in an RTF system of this type thecommunication station always becomes active first. An interrogationsignal will be output by the communication station, which interrogationsignal is received by those ID tags that are within a communicationrange of the communication station, whereupon these ID tags each outputa response signal to the communication station. Such a response signalmay contain, for example, a characteristic signal, which characteristicsignal in each case signifies an ID tag and as a result is used by thecommunication station to distinguish the ID tags from one another. Bymeans of a specific communication protocol, such a communication stationis able to unambiguously recognize response signals sent out by variousID tags, in the course of an inventorying process.

In a Tag Talks First (TTF) system which is likewise used publicly andhas been known for a long time, it is possible for an ID tag to becomeactive on its own, without having to be interrogated for this purpose bya communication station. Such an ID tag itself outputs an identificationsignal, which identification signal is received by a suitablecommunication station, after which further communication between the twoID communication partner devices is carried out in accordance with adefined communication protocol.

In an RTF system, an ID tag that is designed for a TTF system or thathas a TTF mode causes a disruption in communication in the RTF systemand cannot therefore be used in an RTF system. For certain applications,however, the use of such ID tags for the TTF system in an RTF system isvery advantageous and desirable.

The document WO 02/41650 A1 discloses an ID tag which can be used inboth systems. In the case of such a known ID tag, a changeover betweentwo modes, that is to say between two communication modes, can becarried out, to be specific between a mode which is required for use inan RTF system and a mode which is required for use in a TTF system. Sucha changeover is in this case carried out by activation means such that,in storage means of the ID tag, a bit value can be set or erased bymeans of a command transmitted by a communication station, wherein thecommunication mode is adjusted depending on the set bit value. Adisadvantage of the known method and the known ID tag is that the ID tagmust be programmed in advance for either the one application or theother application, that is to say the bit value has to be set by meansof a command, and this takes place, for example, as early as when the IDtag is produced or when the ID tag is initialized. An ID tag that isprogrammed for use in one system, that is to say for example an ID tagthat is programmed for a TTF system, cannot function in another system,that is to say for example in an RTF system, or will cause a disruptionin such a system, and this is disadvantageous. Where appropriate,reprogramming may be effected; however, this requires a specificcommunication station which is suitable for this purpose and which mustservice a suitable communication protocol. This is a condition that isoften not met and can be laborious and expensive, which isdisadvantageous.

It is an object of the invention to eliminate the abovementioneddisadvantages and to produce an improved method and an improvedintegrated circuit for an ID communication partner device designed as acommunication station, and an improved ID communication partner devicedesigned as a communication station, and an improved integrated circuitfor an ID communication partner device designed as a data carrier, andan improved ID communication partner device designed as a data carrier.

To achieve the abovementioned object, a method according to theinvention is provided with features according to the invention, so thata method according to the invention can be characterized as follows,namely:

A method for activating a desired communication mode of an IDcommunication partner device from a group of possible communicationmodes, which group comprises at least a first mode and a second mode,wherein the ID communication partner device and at least one other IDcommunication partner device are brought into a communication connectionand wherein a carrier signal is output by the at least one other IDcommunication partner device, which carrier signal is received by the IDcommunication partner device, and wherein the carrier signal isrepeatedly designated by at least one mode activation signal by means ofthe at least one other ID communication partner device, and wherein thepresence of the mode activation signal is recognized by the IDcommunication partner device, giving a recognition result signal, andwherein, as a function of the recognition result signal, the desiredcommunication mode of the ID communication partner device is activated.

To achieve the abovementioned object, an integrated circuit for an IDcommunication partner device designed as a communication station,according to the invention, is also provided with features according tothe invention, so that such an integrated circuit according to theinvention can be characterized as follows, namely:

Integrated circuit for an ID communication partner device designed as acommunication station, which integrated circuit comprises the followingmeans:

Output means for outputting a carrier signal, which carrier signal canbe received by an ID communication partner device, and generation meansfor generating at least one mode activation signal, and designationmeans, by means of which the carrier signal can be repeatedly designatedby the at least one mode activation signal.

To achieve the abovementioned object, an ID communication partner devicedesigned as a communication station, according to the invention, is alsoprovided with features according to the invention, so that such an IDcommunication partner device according to the invention can becharacterized as follows, namely:

ID communication partner device, which is designed as a communicationstation and which is provided with an integrated circuit for an IDcommunication partner device designed as a communication station,according to the invention.

To achieve the abovementioned object, an integrated circuit for an IDcommunication partner device designed as a data carrier, according tothe invention, is also provided with features according to theinvention, so that such an integrated circuit according to the inventioncan be characterized as follows, namely:

Integrated circuit for an ID communication partner device designed as adata carrier, which integrated circuit comprises the following means:

Activation means for activating a desired communication mode of the IDcommunication partner device from a group of possible communicationmodes and storage means for storing mode control data of the group ofpossible communication modes, which group comprises at least a firstmode and a second mode, and reception means for receiving a carriersignal that is output by an ID communication partner device and isdesignated with a mode activation signal, and recognition means forrecognizing the presence of the at least one mode activation signal, bymeans of which recognition means a recognition result signal can begenerated, as a function of which recognition result signal theactivation of the desired communication mode of the ID communicationpartner device can be activated by the activation means.

To achieve the abovementioned object, an ID communication partner devicedesigned as a data carrier, according to the invention, is also providedwith features according to the invention, so that such an IDcommunication partner device according to the invention can becharacterized as follows, namely:

ID communication partner device, which is designed as a data carrier andwhich is provided with an integrated circuit for an ID communicationpartner device designed as a data carrier, according to the invention.

By providing the features according to the invention, the situation isadvantageously and simply achieved that, when using ID communicationpartner devices designed according to the invention, the IDcommunication partner devices designed as data carriers canautomatically recognize which communication mode is to be activated, sothat the relevant data carrier can itself start communication whereappropriate, without having to await an interrogation, and such a datacarrier can be used without disruption even in communication systems inwhich an ID communication partner device designed as a communicationstation, in the capacity of a central communication control unit,determines the communication mode, wherein all data carriers located inthe communication range of the communication station may communicatewith the communication station when interrogated by the latter.

By providing certain measures in accordance with an embodiment of theinvention, the advantage is obtained that the ID communication partnerdevice designed as a data carrier can be used in known and widespreadcommunication systems.

By providing certain measures in accordance with an embodiment of theinvention, the advantage is obtained that the mode activation signal canbe generated in a relatively simple manner.

By providing certain measures in accordance with an embodiment of theinvention, the situation is advantageously obtained that a continuouslydesignated carrier signal can be used in the communication system andthe continuously designated carrier signal can be demodulated in thecommunication stations, which are in each case designed as datacarriers, by means of a simple demodulator.

By providing certain measures in accordance with an embodiment of theinvention, the situation is advantageously obtained that a continuouslydesignated carrier signal can be used in the communication system andthe continuously designated carrier signal can be detected in thosecommunication partner devices, which are designed as data carriers, bymeans of a simple filter.

In the method according to the invention or in an ID communicationpartner device according to the invention that is designed as acommunication station, the designation of the carrier signal may takeplace continuously. However, it has proven to be particularlyadvantageous when certain measures in accordance with an embodiment ofthe invention are provided. As a result, the situation is obtained thatrelatively simple demodulation methods can be used in the recognition ofthe mode activation signal in the communication partner devices whichare in each case designed as data carriers, which demodulation methodsmay otherwise have a disruptive effect during recognition of thetransmitted signals in the event of continuous designation of thecarrier signal and simultaneous use of the carrier signal to transmitcommand signals.

In an ID communication partner device according to the invention that isdesigned as a communication station, for designation of the carriersignal a designation start point and designation duration can be set orpredefined manually by an operator. However, it has proven to beparticularly advantageous when certain measures in accordance with anembodiment of the invention are provided. As a result, the situation isobtained that, in an ID communication partner device designed as acommunication station, the designation start point and the designationduration can be determined automatically for designation of the carriersignal.

The abovementioned aspects and other aspects of the invention emergefrom the example of an embodiment which is described below, and areexplained on the basis of said example of an embodiment.

The invention will be further described with reference to an example ofan embodiment shown in the drawings to which, however, the invention isnot restricted.

FIG. 1 shows schematically, in the form of a block diagram, those partsof ID communication partner devices according to the invention which areessential in the present context, which ID communication partner deviceseach contain an integrated circuit according to the invention.

FIG. 2 shows schematically, in the form of a signal-time diagram,commands and signals transmitted between the ID communication partnerdevices.

FIG. 1 shows an RFID communication system 1 with RFID communicationpartner devices in a communication range CA, which communication rangeCA is illustrated by a dashed line. Here, one RFID communication partnerdevice is designed as a data carrier 2, another RFID communicationpartner device is designed as a communication station 4 and a furtherRFID communication partner device is designed as a data carrier 2′,wherein the data carrier 2 and the communication station 4 are shown inmore detail.

The communication station 4, which may likewise be referred to as thereader station 4, is designed for contactless communication with the twodata carriers 2 and 2′.

The reader station 4 has transmission means 5, which form both sendingmeans and receiving means, define the communication range CA duringsending, are designed to send a reader signal RS at a frequency of 13.56MHz and are designed to receive a data carrier signal TS from the twodata carriers 2 and 2′. Such transmission means 5 have been known for along time, for example from the document U.S. Pat. No. 5,537,105 A1, thedisclosure of which is hereby incorporated by way of reference.

The reader station 4 furthermore has carrier signal generation means 6,modulation means 7 and demodulation means 8 for purposes which arelikewise known. The reader station 4 furthermore has processing means 9that are formed by a microprocessor, which microprocessor forms thefollowing means: command signal generation means 10 for generatingcommand signals and for outputting the command signals to the modulationmeans 7, reception signal processing means 11 which are designed toprocess a demodulated reception signal output by the demodulation means8, and also sequence control means 12 for controlling the command signalgeneration means 10, the reception signal processing means 11 and othermeans that are not shown.

The sequence control means 12 comprise: communication status recognitionmeans 13, which are designed to recognize a communication status, andcommunication mode changeover means 14, which in this case are designedfor changeover between two communication modes.

The reader station 4 furthermore has storage means 15, which areconnected to the processing means 9 and the sequence control means 12and which are designed to store mode control data of the twocommunication modes and to store received information.

The data carriers 2 and 2′ have transmission means 16 for sending thedata carrier signal TS and for receiving the reader signal RS output bythe reader station 4. The data carriers 2 and 2′ are formed by what areknown as passive data carriers and have clock signal generation meansand operating voltage generation means, which are not shown in anygreater detail, with which clock signal generation means or operatingvoltage generation means a clock signal or the operating voltage foroperating the data carriers is derived from the signals output by thereader station 4, for example from the reader signal RS. The datacarriers 2 and 2′ are designed to send response information ANS andother information, during which sending an unmodulated carrier signaloutput by the reader station 4 is modulated using a subcarrier signal inaccordance with a load modulation depending on the response information.For this purpose, the data carrier 2 or 2′ has an integrated circuit 3,which integrated circuit 3 has processing means 17 that are formed interalia by a microcomputer, which processing means 17 output the responseinformation ANS via modulation means 21 to the transmission means 16,with the aid of command/response generation means 18, sequence controlmeans 19 and data carrier storage means 20 that are contained in saidprocessing means 17.

Furthermore, the integrated circuit 3 has command signal demodulationmeans 22, which are designed to demodulate the reader signal RS that hasbeen received by the transmission means 16 and modulated in accordancewith command signals. The processing means 17 furthermore comprisecommand signal recognition means 23, which are designed to recognize thecommand signals and to output these command signals to the sequencecontrol means 19. Such command/response generation means 18, sequencecontrol means 19, data carrier storage means 20, modulation means 21,command signal demodulation means 22 and command signal recognitionmeans 23 are known, for example, from the European patent applicationhaving the application number EP 02 100 399.1 (PHAT020020 EP-P), whichapplication is claimed as priority in an international application withthe application number IB03/01440, the disclosure of which isincorporated herein by way of reference.

The integrated circuit 3 furthermore has RTF/TTF activation signalrecognition means 24, which are designed to recognize a reader signal RSdesignated or labeled with an RTF/TTF activation signal, and this isdescribed in greater detail hereinbelow.

The processing means 17 furthermore have control data storage means 25for storing mode control data of the two communication modes, andactivation means 28, wherein a storage block 26 for the control data ofa TTF mode and a storage block 27 for the control data of an RTF modeare stored in the control data storage means 25. The control data of theTTF and RTF modes are designed here as software code sections, and thecontrol data storage means 25 are designed as a nonvolatile memory ROM.It may be mentioned that the control data storage means 25 may bedesigned as an EPROM. It may also be mentioned that the control data ofthe TTF and RTF modes may likewise be formed by a hardwired logiccircuit. More details regarding the RTF/TTF activation signalrecognition means 24, control data storage means 25 and activation means28 are given hereinbelow.

Using an example of an embodiment and FIG. 2, the functioning of the twodata carriers 2 and 2′ according to the invention and of the readerstation 4 according to the invention is explained in more detail below.

In one very common application, the RTF mode is initially set in thereader station 4 by means of the communication mode changeover means 14,and a large number of data carriers (not shown in any more detail), withwhich an RTF mode can be carried out, are brought into communicationconnection with the reader station 4, by these data carriers beingbrought into the communication range CA of the reader station 4. Thesedata carriers may for example form electronic tickets for an undergroundrailway system, which tickets are brought into the communication rangeCA of the reader station 4 prior to or at the start of the journey, inorder to pay the price of the journey. Before reading of data containedin each of these data carriers and/or writing of data to each of thesedata carriers can be carried out, what is known as inventorying of atleast one data carrier must be carried out by the reader station 4 thatis contactlessly communicating with said data carriers. In the course ofsuch inventorying, for each data carrier identification data ID that issignificant for the relevant data carrier is transmitted from therelevant data carrier to the reader station 4 and stored in the readerstation 4, so that in the reader station 4 the identification data ID ofall data carriers that are in communication connection with the readerstation 4 is known, as a result of which it is possible for the readerstation 4 to use the identification data ID that signify the datacarriers to enter into communication connection with each data carrierin a targeted and unmistakable manner, in order for example to readuseful data from the relevant data carrier or to store useful data inthe relevant data carrier. It may be mentioned that identification dataID does not have to be determined for all data carriers that can bebrought into communication connection with the reader station 4, butrather it is enough to know the identification data ID of a data carrierresponding first.

In accordance with the application example, the data carrier 2 and thedata carrier 2′ have what is known as a multitag functionality or thetwo data carriers 2 and 2′ are each designed as a multitag card whichhas a large number of authorizations, for example authorizations toaccess an underground railway system or a parking lot, etc. A user orproprietor of the data carrier 2 and another proprietor of the datacarrier 2′ then advantageously have the possibility, in a very simplemanner, to exchange such access authorizations or to transmit suchaccess authorizations between the two data carriers 2 and 2′. Forexample, a daily pass for an underground railway system or theauthorization to use an underground railway system can be passed fromone user to another user without the multitag card, which still containsa large number of further authorizations, having to be handed over.

Such a method and a communication sequence in relation thereto betweenthe RFID communication partner devices, that is to say the data carriers2 and 2′ and the reader station 4, is described below on the basis ofFIG. 2. FIG. 2 shows time sequences of communication signals both of thereader station 4 and of the two data carriers 2 and 2′, wherein thereader signal of the reader station 4 is denoted RS, the data carriersignal of the data carrier 2 is denoted TS1 and the data carrier signalof the data carrier 2′ is denoted TS2.

It is assumed that, at the beginning of the communication sequence, onlythe data carrier 2 is in the communication range CA of the readerstation 4. The reader station 4 is initially set to the RTF mode andoutputs, from a time t1 to a time t2, an inventorying command IGCO asreader signal RS, which inventorying command IGCO is generated by thecommand signal generation means 10 and output to the modulation means 7.Said inventorying command IGCO is received and recognized by the datacarrier 2. Since there is still no RTF/TTF activation signal, theRTF/TTF activation signal recognition means 24 of the data carrier 2output a recognition result signal RRS to the activation means 28 suchthat the RTF mode is activated. In accordance with the RTF mode of thedata carrier 2, the data carrier signal TS1 along with a response signalANS1 is output by this data carrier 2 from a time t3 to a time t4, andis received by the reader station 4, wherein the response signal ANS1 isin this case formed by an identification number or serial number, whichserial number is stored in the data carrier storage means 20.Thereafter, the reader station 4 outputs, from a time t5 to a time t6, aselection command SEL-1, which selection command SEL-1 is received bythe data carrier 2 and is acknowledged by an acknowledgement signalACK-1. Following the acknowledgement signal ACK-1, the reader station 4outputs a deselection command DSEL-1, which deselection command DSEL-1is received by the data carrier 2 and is in turn acknowledged by thelatter by means of an acknowledgement signal ACK1. The communication bythe reader station 4 is now terminated and a communication status tothis effect is recognized by the communication status recognition means13 of the reader station 4. Subsequently, said communication statusrecognition means 13 initiate changeover of the communication mode ofthe reader station 4, by the communication mode changeover means 14, tothe TTF mode, in which TTF mode the reader station 4 no longer has tostart communication since a suitable data carrier can also start such acommunication by itself. At the same time, the communication statusrecognition means 13 initiate generation of an RTF/TTF activation signalAS by generation means 29 for generating such an RTF/TTF activationsignal, which generation means 29 are connected to the communicationstatus recognition means 13, and outputting of said RTF/TTF activationsignal AS to the modulation means 7. In the modulation means 7, from atime t13, the carrier signal CS is continually designated with theRTF/TTF activation signal AS and output via the transmission means 5,precisely as the reader signal RS with the RTF/TTF activation signal.The RTF/TTF activation signal is in the present case formed by asinusoidal signal, the frequency of which is selected as an integermultiple of the subcarrier frequency used in the load modulation. It maybe mentioned that the frequency of the sinusoidal signal may likewise beselected to be substantially lower than the frequency of the subcarriersignal, for example a quarter or a sixth.

It may furthermore be mentioned that the RTF/TTF activation signal maybe formed by another signal form, for example by a triangular form orrectangular form or a sawtooth form. It is important that when, as inthe present case, the carrier signal CS is simultaneously used totransmit command signals, the frequency spectra of such command signalsand of the RTF/TTF activation signal AS do not overlap one another,because such overlapping would lead to disruptions in the recognition ofthe transmitted signals in the RFID communication partner devicesreceiving these signals.

In accordance with the application example, the data carrier 2′ comesinto the communication range CA of the reader station 4 after the timet13 and before a time t14. The RTF/TTF activation signal recognitionmeans 24 of the data carrier 2′ recognize, immediately thereafter, thata reader signal RS designated with an RTF/TTF activation signal AS ispresent and subsequently initiate the bringing of the data carrier 2′into the TTF mode, by outputting the recognition result signal RRS tothe activation means 28. In the present case, the RTF/TTF activationsignal recognition means 24 are formed by a simple demodulator, whichdemodulator is tuned to the frequency of the RTF/TTF activation signalAS, wherein the demodulation is carried out by means of correlation. Itmay be mentioned that the RTF/TTF activation signal recognition means 24may likewise be formed by a simple filter if the frequency of theRTF/TTF activation signal AS is selected to be lower than the frequencyof the subcarrier signal.

The data carrier 2′ can then itself start communication with the otherRFID communication partner devices or start an inventorying process. Inthe present case, an inventorying process is started and carried out inaccordance with a time slot method, wherein the data carrier 2′ outputsan enquiry command or inventorying command IGCO2 from the time t14 to atime t15, which inventorying command IGCO2 is received by the readerstation 4 and the data carrier 2. In this inventorying process, in eachcase a response signal is generated and output by the two receiving RFIDcommunication partner devices, wherein the data carrier 2 outputs aresponse signal ANS1 from a time t16 to a time t17 and the readerstation 4 outputs a response signal ANS0 from a time t18 to a time t19.It may be mentioned that a different inventorying process may likewisebe carried out, for example a process known from the European patentapplication having the application number EP 02 102 343.7 (PHAT020058EP-P), which application is claimed as priority in an internationalapplication with the application number IB03/03956, the disclosure ofwhich is hereby incorporated by way of reference.

The two response signals ANS1 and ANS0 are in the present case formed byidentification signals and are received and evaluated by the datacarrier 2′. Subsequently, the data carrier 2′ outputs a selectioncommand SEL-1 from a time t20 to a time t21, as a result of which thedata carrier 2′ can carry out a further communication sequence with thedata carrier 2. In such a further communication sequence, for example,useful data can be exchanged between the data carriers 2 and 2′, whichuseful data in the present case is formed by the authorization data.

In accordance with a further example of an embodiment of the invention,the communication status recognition means 13 may be omitted from areader station. In this case, such a reader station can then beconnected to a host computer, wherein a changeover of the communicationmode of such a reader station and/or the activation of the designationof the carrier signal can be initiated by an administrator using thehost computer. Likewise, such a reader station may be designed so ascontinually to operate in a TTF communication mode and to output adesignated carrier signal.

It may be mentioned that such a further communication sequence mayinclude the reader station 4, for example in order to be able to use thereader station 4 to carry out security enquiries, so that only dataallowed according to an authorization can be exchanged between the datacarriers 2 and 2′.

It may be mentioned that separate carrier signals can be used for theRTF/TTF activation signal AS and for the command signals.

It may also be mentioned that the designation of the carrier signal withthe RTF/TTF activation signal AS can be carried out at predefined timeintervals, that is to say that a designation with defined RTF/TTFactivation signal sequences takes place, which RTF/TTF activation signalsequences repeat. Such an RTF/TTF activation signal sequence thereforehas to be selected such that there is no possibility of confusion with acommand signal. A time period between two successive RTF/TTF activationsignal sequences should be at least as long as a command signal.

It may furthermore be mentioned that the reader station 4 may likewisebe formed by a data carrier 2, wherein such a data carrier 2 has thesame means for communication with other data carriers as such a readerstation 4.

Using the measures according to the invention, not only is it possiblefor an automatic recognition of what is known as an RTF mode and what isknown as a TTF mode and a subsequent automatic activation of therespectively desired mode in an ID communication partner device designedas a data carrier (transponder) to be carried out, but also it ispossible for other types of mode recognition and mode activation to becarried out, for example a recognition of what is known as a short-rangemode and what is known as a long-range mode and subsequently anactivation of one of these two modes. A recognition of a time-divisionalmode and a frequency-divisional mode and a code-divisional mode and asubsequent activation of one of these three modes is also possible.

As described above, the carrier signal CS is repeatedly designated bythe mode activation signal AS, wherein this designation can take placesuch that it is continually repeated or such that it is repeated only attime intervals, wherein the time intervals may be the same length or maybe of different lengths on a random basis.

A description is given above, on the basis of FIGS. 1 and 2, of what areknown as RFID communication partner devices, wherein RFID is theabbreviation for “radio frequency identification”. However, the measuresaccording to the invention are not restricted to RFID communicationpartner devices which communicate with one another in the RF range(RF=radio frequency), but rather they can also advantageously be used inother systems which communicate with one another in the MHz range or GHzrange.

1. A method for activating a desired communication mode of an IDcommunication partner device from a group of possible communicationmodes, which group comprises at least a first mode and a second mode,wherein the ID communication partner device and at least one other IDcommunication partner device are brought into a communication connectionand wherein a carrier signal is output by the at least one other IDcommunication partner device, which carrier signal is received by the IDcommunication partner device, and wherein the carrier signal isrepeatedly designated by at least one mode activation signal by the atleast one other ID communication partner device, and wherein the absenceor the presence of the mode activation signal is recognized by the IDcommunication partner device, giving a recognition result signal, andwherein, as a function of the recognition result signal, the desiredcommunication mode of the ID communication partner device is activated,the ID communication partner device being always activated to the samemode selected from a Reader Talks First (RTF) mode and a Tag Talks First(TTF) mode when the recognition result signal indicates the absence ofthe mode activation signal, the ID communication partner device beingalways activated to the other mode of the RTF mode and the TTF mode whenthe recognition result signal indicates the presence of the modeactivation signal, the ID communication partner device being configuredto operate in the RTF mode and the TTF mode.
 2. A method as claimed inclaim 1, wherein the at least one mode activation signal is formed by atleast one sinusoidal signal and the carrier signal is designated by amodulation using the at least one sinusoidal signal.
 3. A method asclaimed in claim 2, wherein the mode activation signal is recognized bycorrelation.
 4. A method as claimed in claim 2, wherein the modeactivation signal is recognized by filtering out the sinusoidal signal.5. A method as claimed in claim 1, wherein the carrier signal isdesignated only at predefined time intervals.
 6. A method as claimed inclaim 1, wherein a recognition of a communication status is carried outand wherein the repeated designation of the carrier signal by the modeactivation signal is carried out as a function of the communicationstatus.
 7. An integrated circuit for an ID communication partner devicedesigned as a communication station, which integrated circuit comprisesthe following means: output means for outputting a carrier signal, whichcarrier signal can be received by another ID communication partnerdevice, generation means for generating at least one mode activationsignal, and designation means for repeatedly designating the carriersignal with the at least one mode activation signal such that the atleast one mode activation signal is selectively present, the at leastone mode activation signal being configured to be recognized by theanother ID communication partner device to always activate the same modeselected from a Reader Talks First (RTF) mode and a Tag Talks First(TTF) mode when the presence of the at least one mode activation signalis recognized, the another ID communication partner being furtherconfigured to always activate the other mode of the RTF mode and the TTFmode when the absence of the at least one mode activation signal isrecognized, the another ID communication partner device being configuredto operate in the RTF mode and the TTF mode.
 8. An integrated circuit asclaimed in claim 7, wherein the generation means are designed to formthe at least one mode activation signal using at least one sinusoidalsignal, and wherein the designation means are designed to designate thecarrier signal with the at least one sinusoidal signal using modulation.9. An integrated circuit as claimed in claim 7, wherein the designationmeans are designed to designate the carrier signal only at predefinedtime intervals.
 10. An integrated circuit as claimed in claim 7, whereincommunication status recognition means are also provided, by means ofwhich a communication status of the ID communication partner device canbe recognized, and wherein the designation means are designed torepeatedly designate the carrier signal by the mode activation signal asa function of the communication status.
 11. An ID communication partnerdevice, which is designed as a communication station and which isprovided with an integrated circuit as claimed in claim
 7. 12. Anintegrated circuit for an ID communication partner device designed as adata carrier, which integrated circuit comprises the following means:activation means for activating a desired communication mode of the IDcommunication partner device from a group of possible communicationmodes, the desired communication mode being either a Reader Talks First(RTF) mode or a Tag Talks First (TTF) mode, the activation means beingconfigured to switch between the RTF mode and the TTF mode, storagemeans for storing mode control data of the group of possiblecommunication modes, which group comprises at least a first mode and asecond mode, reception means for receiving a carrier signal that isoutput by another ID communication partner device and is designated witha mode activation signal, and recognition means for recognizing theabsence or the presence of the at least one mode activation signal, bymeans of which recognition means a recognition result signal can begenerated, as a function of which recognition result signal theactivation of the desired communication mode of the ID communicationpartner device can be activated by the activation means, wherein theactivation means is configured to always activate the ID communicationpartner device to the same mode selected from the RTF mode and the TTFmode when the recognition result signal indicates the absence of the atleast one mode activation signal, the activation means being furtherconfigured to always activate the ID communication partner device to theother mode of the RTF mode and the TTF mode when the recognition resultsignal indicates the presence of the at least one mode activationsignal.
 13. An integrated circuit as claimed in claim 12, wherein therecognition means are designed to carry out the recognition of thepresence of the at least one mode activation signal by a demodulationusing correlation.
 14. An integrated circuit as claimed in claim 12,wherein the recognition means are designed to recognize the presence ofthe at least one mode activation signal by filtering out this signal.15. An ID communication partner device, which is designed as a datacarrier and which is provided with an integrated circuit as claimed inclaim 12.